Special forces officers armed with guns locked up 30 crew members on the Arctic Sunrise icebreaker ship after lowering themselves onto the deck with ropes from a helicopter.

The Federal Government is seeking information from Russia about the welfare of an Australian national and an Australian resident who were among the detained activists.

Greenpeace Australia Pacific identified the two men as 59-year-old radio officer Colin Russell, from Tasmania, and British-born Alex Harris, who works in the organisation's Sydney office.

"The decision was taken that the Arctic Sunrise will be taken to the port of Murmansk for further legal procedures," a spokeswoman for the Murmansk region's border guards - a branch of the FSB security service - told the RIA Novosti news agency.

She said the captain had been questioned but a full investigation would take place when the ship reaches Murmansk, about 1,485 kilometres north of Moscow.

According to the Coast Guard on Russian radio, our ship has not been arrested. They are still deciding what to do with our activists.

He said Greenpeace had not been able to communicate with the ship and those on board have been denied access to legal representation.

"They were there to peacefully highlight the dreadful threat to the Arctic environment posed by the Russian oil giant Gazprom, which is trying to be the first company in history to extract oil from the Arctic," he said.

"All the activists had tried to do a day or so earlier was to get on board the oil platform, I understand, in order to hold up a banner to highlight that.

"It is a very well established principle of international law that a nation state does not board a vessel that is peacefully traversing international waters."

He said the activists were locked in the mess but allowed out to go to the toilet or smoke.

Greenpeace said border guards on Wednesday had detained two activists who were attempting to scale Gazprom's Prirazlomnaya oil platform and took them on board their patrol boat.

The border guards later returned the two activists from Finland and Switzerland to the Arctic Sunrise and locked them up with their crewmates, Greenpeace said.

Greenpeace said the Dutch-flagged Arctic Sunrise was in international waters at the time of the boarding, in the south-eastern part of the Barents Sea, which lies to the north of Norway and western Russia.

Russia's foreign ministry on Thursday called in the Dutch ambassador to Moscow to complain about the protest.

Greenpeace is campaigning against surveying of oil and gas fields on the Arctic shelf, arguing that any oil leak would be catastrophic in the pristine environment and impossible to bring under control.

But the prospect of more accessible energy riches as global warming gradually melts the sea ice is prompting rivalry between Russia, Norway and Canada to explore and exploit region.